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DNA. Nucleotides. Nitrogen Base. Phosphate. Ribose (Sugar). Nitrogen Bases. Nitrogen Base Pairs Always – Complementary Base Pair. DNA Replication. Copying of DNA during S1 phase of interphase. Semi-Conservative. Replication.
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Nucleotides Nitrogen Base Phosphate Ribose (Sugar)
Nitrogen Bases Nitrogen Base Pairs Always – Complementary Base Pair
DNA Replication • Copying of DNA during • S1 phase of interphase • Semi-Conservative
Replication • Helicase unwinds the double helix by breaking the hydrogen bonds • The single strands act as templates for new strands. Free nucleotides are present in large numbers around the replication fork. The bases of these nucleotides form hydrogen bonds with the bases of the parent strand. DNA polymerase links the bases together • The daughter DNA molecule rewind into a double helix.
DNA Transcription • Genes from DNA are not directly used to direct the synthesis of polypeptides • A molecule mRNA is made using DNA as a template • Complementary base pairing occurs in Transcription except Uracil pairs with Adenine
DNA Transcription • Helicase uncoils the DNA helix and the two strands separate • Free RNA nucleotides are assembled using one of the two DNA strands as the template • RNA polymerase links the RNA nucleotides together to form a strand of mRNA • The mRNA strand separates from the DNA • It leaves the nucleus via the nuclear pores
DNA Translation • Carried out in the ribosomes using mRNA and tRNA • mRNA binds to the ribosome. mRNA consists of a series of triplet codons which code for an amino acid